The present invention relates to a collimator, as well as an X-ray irradiator and an X-ray apparatus. Particularly, the invention is concerned with a collimator for restricting an irradiation range of X-ray, as well as an X-ray irradiator and an X-ray apparatus both provided with such a collimator.
In an X-ray irradiator there is used a collimator for restricting an irradiation range of X-ray. The collimator has an aperture permitting X-ray to pass therethrough and has a structure such that X-ray cannot pass through the collimator except the aperture. With this structure, the irradiation range of X-ray can be adjusted.
A collimator having a variable aperture is provided with movable plate members, that is, blades having X-ray absorbability. As the blades there are used a pair of blades opposed to each other at respective end faces. The pair of blades are movable in directions opposite to each other in a plane parallel to their surfaces. For expanding the aperture, the pair of blades are moved in directions away from each other, while for narrowing the aperture, the blades are moved toward each other.
As a collimator developed for reducing the size thereof without sacrificing a variable range of an aperture there is known one in which blades are constructed of a flexible material and are wound round drums and, for expanding the aperture, are wound inwards round the drums, while for narrowing the aperture, they are paid out from the drums (see, for example, Patent Literature 1).
[Patent Literature]
Japanese Published Unexamined Patent Application No. 2002-355242 (pages 2 to 3, FIGS. 1 to 2)
The above known collimator involves the problem that it is necessary to use a special material flexible and superior in X-ray absorbability as the blase material.